d and f BLOCK ELEMENTS

What is the main consequence of the lanthanoid contraction mentioned regarding the third transition series?

• It makes the radii of third series elements similar to the corresponding second series elements
• It makes the third series elements more reactive than the first series
• It eliminates the transition metals
• It makes the third series elements behave like Lanthanoids

Why is the decrease in ionic radii of M³⁺ ions described as 'fairly regular' while the atomic radii decrease is 'not quite regular'?

• The ionic radii trend directly reflects nuclear charge and f-electron shielding, while atomic radii are influenced by additional factors
• Ionic radii are always smaller than atomic radii
• Atomic radii are measured differently
• The text contains a contradiction

What is the primary factor that makes the +3 oxidation state predominant for all Lanthanoids?

• The formation of Ln³⁺ ions results in stable 4fⁿ electronic configurations
• The +3 state requires the least energy to achieve
• The +3 state is the only state Lanthanoids can exhibit
• The +3 state makes Lanthanoids behave like alkali metals

Which statement best describes the trend in atomic radii across the Lanthanoid series?

• There is an overall decrease, but it is not perfectly regular
• There is a perfectly regular decrease
• There is no significant change
• There is an overall increase

In the context of Lanthanoid ions, what does the variable 'n' represent in the general electronic configuration 4fⁿ for Ln³⁺ ions?

• The number of electrons in the 4f subshell, ranging from 1 to 14
• The atomic number of the Lanthanoid
• The principal quantum number of the outermost shell
• The number of electrons lost to form the ion